| 摘要 |
PROBLEM TO BE SOLVED: To provide an image signal processing circuit capable of accelerating operation of an automatic exposure control function in moving from a bright environment to a dark environment. SOLUTION: Automatic exposure control was performed conventionally using an output value of a gamma correction circuit. Since the control is performed so as to move a dark image to the center of gradations in moving from a dark environment to a bright environment, however, when the image becomes bright, gradations are skipped, so that it is necessary to perform processing for bringing the bright image to the center of gradations over and over again. Therefore, automatic exposure control is performed using an input value of the gamma correction circuit. In such a case, a gradation value of a dark picture becomes small, so that much gradations up to an upper limit of gradation value can be secured. Further, the number of times of processing until bringing the bright image to the center of gradations can be reduced, and followup performance of automatic exposure control is improved. COPYRIGHT: (C)2009,JPO&INPIT
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